Though you do not cast spells, you can learn to manipulate your eldritch energies in ways previously unknown. Choose any one spell that a sorcerer of the same level as you could cast. You gain this spell as a invocation. If the original spell has a duration of concentration, it is instead changed to 1 minute/level. To gain this spell, however, you must give up any number of invocations that you already know with with a spell level of equivalent value to the spell you are gaining as an invocation. You have a caster level of 6 lower than your maximum when casting an invocation gained by this feat for purposes of damage and other effects.